<!DOCTYPE html>
<html>
<head>
	<title>验证码</title>
</head>
<script type="text/javascript">
	function changing(){
    	document.getElementById('checkpic').src="getCode.php?"+Math.random();
	} 
</script>
<body>
		<img id="checkpic" onclick="changing()" src='getCode.php' />
</body>
</html>